I have designed a temperature control unit with a Proportional Integral (PI) Controller and I intend to use ziegler nichols method of PI tuning. But for that I need to measure the time period of fast oscillations in the temperature output.
Sensors, which give an output voltage corresponding to temperature, have time constants in the range of seconds which makes it unsuitable for measuring such fast oscillations. Please suggest ways of measuring fast oscillations in the temperature output.